Golf club

ABSTRACT

A golf club having a shaft (3) and a club head (2) which is connected to a shank portion (4) of the shaft at its heel end (31) so that it can be rotated around the axis of the shank portion. The configuration of the shank portion is such that the shaft axis and the shank axis intersect at about the bottom of the heel end of the club head so that rotating the club head around the shank axis causes the angle between the club face (30) and the shaft (3) to change.

BACKGROUND OF THE INVENTION

This invention relates to a golf club.

A golf club with an adjustable head can be used in place of two or moreclubs with different head configurations. Most notably, variation in theangle between the face of the club head and the shaft can be adjusted tovary the degree of loft imparted to a ball when struck. Adjustable golfclubs suffer from the disadvantage that, through the designmodifications necessary to incorporate adjustment, or through playbetween the adjustable components, the feel of the club to the player isunacceptably different from that of a conventional unadjustable club.

GB-A-2109249 discloses a golf club in which the loft of the head can beadjusted. The head can be fitted on an end portion of the shaft which isarranged at an angle to the main body of the shaft. The head can berotated about the angled end portion. The effective angle between theclub face and the shaft is altered as the club head is rotated about thecranked end.

The club disclosed in GB-A-2109249 suffers from the disadvantage thatthe feel to the player is unacceptably different from that of aconventional unadjustable club due to the requirement for the crankedend of the shaft for mounting the club head.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a golf club in which the head is mountedon a shank portion at the end of the shaft. The head can be rotatedaround an axis defined by the shank portion, the axes defined by theshank portion and the shaft intersecting at about the bottom of the heelof the head.

Accordingly, in one aspect, the invention provides a golf club whichcomprises (a) a shaft with a shaft axis, the shaft having a shankportion with a shank axis, and (b) a head which has a heel end and aclub face for contacting a golf ball when the club is swung in use, thehead being attached to the shank portion of the shaft at its heel end sothat it can be rotated around the shank axis, the configuration of theshank portion being such that the shaft axis and the shank axisintersect at about the bottom of the heel end of the club head so thatrotating the club head around the shank axis causes the angle betweenthe club face and the shaft to change.

The club of the present invention has the advantage of combining theproperties of adjustment to provide different degrees of loft and a feelwhich more accurately reproduces the feel of a conventional golf club.The club of the invention can provide the player with a range of loftangles while maintaining a desired general location of the club headrelative to the axis of the shaft.

Preferably, the shank portion is configured so that the angle betweenthe shank axis and the vertical when the club is held in its intendedposition for striking a ball is less than about 30°, more preferablyless than about 15°, especially less than about 10°. It is particularlypreferred that the shank portion is configured so that the said angle isbetween 0° and 5°, so that the shank will often be substantiallyvertical when the club is held in its intended position for striking aball.

Preferably, the angle between the shaft axis and the shank axis is atleast about 5°, more preferably at least about 10°, especially at leastabout 15°, and at least about 20° for some applications. Preferably, thesaid angle is less than about 40°, more preferably less than about 30°,especially less than about 25°.

Preferably, the shank portion of the shaft is formed by bending an endportion of the shaft. More preferably, the shank portion of the shaftcomprises a first section which defines the shank axis and a secondsection which extends between the shaft and the first section.

Generally, the angles between the first and second sections of theshank, and between the shaft and the second section of the shank, willbe obtuse angles. Preferably, the angle between the first and secondsections of the shank portion is less than the angle between the saidsecond section and the shaft. The difference between the said angles ispreferably at least about 5°, more preferably at least about 15°,especially at least about 25°. The difference between the said angleswill preferably be less than about 40°, more preferably less than about30°.

The golf club will generally include means for locking the club headagainst rotation about the shank axis.

The connection between the head and the shank portion can be provided byan assembly in which one of the head and the shank portion provides aspigot and the other of the head and the shank portion defines a bore,the head and the shank portion engaging one another by receipt of thespigot in the bore. Preferably, the spigot has (a) a first threadedportion for engaging a thread in the bore, (b) a second threaded portionwhich is threaded in the opposite sense to the first threaded portion,and (c) an internally threaded nut on the second threaded portion tolock the head against rotation relative to the shank portion.

Preferably, the pitch of the thread on the first threaded portion of thespigot is coarser than that of the thread on the second threadedportion. Conveniently, the thread on the first threaded portion is amulti-start thread, and that on the second threaded portion is asingle-start thread. Such a combination of features can provide enhancedaccuracy in adjustment of the club, in particular since small amounts ofmovement of the head can be controlled with relatively large movement ofthe nut.

Preferably, the club includes a blind tapped nut located in the bore andthe spigot includes a third threaded portion which can engage the nut tolock the spigot in the bore.

The spigot might alternatively be internally threaded, and held in placein the bore by means of a threaded fastener such as a screw.

The locking means might be provided by collar portions on the head andthe shank portion which (a) can be rotated relative to one another whenaxially separated, and (b) can be locked together against relativerotation when held axially against one another. The locking of thecollar portions can be achieved by means of interlocking formationsextending generally in the direction of the axis of the collar portions,for example in the form of castellations. The locking means can beprovided by collar portions on the head and the shank portion and anintermediate collar located between the head and the shank portion, thehead and the shank portion bearing formations which engage correspondingformations on the respective facing surfaces of the intermediate collar.The use of an intermediate collar in this way can enable more precisecontrol to be obtained over the adjustment of the club head, for exampleby providing different spacings between formations on the head and theshank portion respectively (and the corresponding facing surfaces of theintermediate collar).

Preferably, the length of the shaft is adjustable. This has theadvantage of allowing the feel of the club to be optimised following anadjustment to the loft. It also has the significant advantage ofallowing the club to be collapsed to a compact configuration, forexample for convenient transportation. This advantage can be importantin circumstances such as when golf equipment is to be transported in avehicle in which there is little space, for example in a car or in avehicle.

The shaft might comprise an inner portion and an outer portion, theinner portion being slidable telescopically within the outer portion toadjust the length of the shaft. There might be more than two portionswhich are capable of sliding telescopically in this way.

The club can include a resiliently deformable member arranged around theinner portion of the shaft, between the inner portion and the internalwall of the outer portion. Such a deformable member can support theinner and outer portions, minimising transverse relative movementbetween the inner and outer members.

Preferably, the club includes locking rings positioned around theresiliently deformable member, by which the member can be axiallycompressed to increase its transverse dimension, to engage the inner andouter portions of the shaft.

Preferably, the resiliently deformable member comprises a tube formedfrom an elastic material. Preferably, the locking rings comprise aplurality of rings formed from a non-resilient material, generally apolymeric material.

When it is adjustable in length, the shaft preferable bears markingswhich enable the shaft to be pre-set at a predetermined desired length.

BRIEF SUMMARY OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention will now be further described by way of example only withreference to the accompanying drawings in which:

FIG. 1 is a schematic representation of an adjustable golf clubaccording to the present invention;

FIGS. 2a, 2b and 2c are each schematic representations of a golf club ofFIG. 1 showing the golf club in each of three working positions;

FIGS. 3a and 3b are exploded representation of a lower portion of thegolf club of FIG. 1 showing the golf club head assembly;

FIGS. 3c, 3d and 3e are schematic representations of further embodimentsof a tapped bush suitable for use in the golf club of FIG. 3b;

FIGS. 4a, 4b, 4c and 4d are exploded representations of the shaft of agolf club according to the invention;

FIGS. 5a, 5b and 5c are schematic representations of a collet in afurther embodiment of the invention in which the collet serves as asecond adjustment means; and

FIG. 6 is a side view, partially in section, of the lower of portion ofanother embodiment of golf club.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, FIG. 1 shows a golf club 1 which comprises agolf club head 2 connected to a shaft 3 by means of a shank portion 4.The golf club has a shaft length set in mid position by adjustment means5 described in more detail below.

The shank portion 4 is formed by bending a shaft. A first section of theshank portion 8 defines an axis and engages the head. A second sectionextends between the first section 8 and the shaft 3. The shaft with itsshank portion defines elbows 6 and 7. The angle at the elbow 6 betweenthe first and second section of the shank portion is smaller than theangle at the elbow 7 between the second section of the shank portion andthe first section.

The golf club 1 is shown in three working positions in FIGS. 2a, 2b and2c. In FIG. 2a, the golf club head 2 is adjusted to a minimum lockedposition for use in putting. Ground level is indicated by referencenumeral 21.

FIG. 2b shows the club head 2 adjusted to mid locked position which isequivalent to a 5 iron conventional club. The associated ground level isindicated by reference numeral 22.

FIG. 2c shows the club head 2 adjusted to a maximum locked positionequivalent to the wedge in a set of conventional unadjustable golfclubs. The associated ground level is indicated by reference numeral 23.

Embodiments of the head assembly of the club 1 of FIG. 1 are shown inFIGS. 3a and 3b in an exploded view. The assembly comprises a head 2which comprises a face 30 and a heel portion 31 in which a bore 32 isformed. The heel portion has a first end and a second end. The face 30further comprises a sole 33 which is angled so that a centre portion 34of the sole 33 makes contact with the ground when the club is used, evenwith a small angular rotation of the face.

The golf club head 2 is attached to the shaft 3 by means of a shankportion 4. The shank portion 4 comprises a first threaded portion 35 anda second threaded portion 36. The shank 4 is shaped to fit in the bore32 in the head, and is kept in place by means of a tapped bush 43 whichitself fits into the bore 32 and is fixed therein, for example by meansof an adhesive. The tapped bush 43 can mate with the first threaded 35of shank 4. The end portion 37 of shank 4 has a plain diameter which isslit along its length to a bore positioned substantially at the centreof the end portion 37. The bore in the end of the shank is tapped toaccept a tapered screw 38. When the shank 4 is positioned in the bore 32in the head, the end portion 37 of the shank is held in position withinthe bore 32 by means of a split bush 39 and a screw 38.

By adjusting the length of engagement of the screw 38 with the endportion 37, the amount of frictional resistance to rotation betweenshank 4 and head 2 can be adjusted.

Referring to FIG. 3b, a golf club head is shown in which the end portion37 and split bush 39 of the FIG. 3a embodiment have been replaced by athird threaded portion 37a and a lock nut 39a respectively. The thirdthreaded portion 37a mates with the lock nut 39a locks the shank 4 tothe head 2 which when rotated to locate against the smaller diameter endof bush 43. The lock nut 39a has a suitable slot for locating a disc orcoin for tightening.

In the FIG. 3b embodiment, the tapped bush 43 is locked between theconical nut 40 and the split bush 39 . However, because of the naturalclearances required between male and female thread forms, a small amountof rotation of the tapped bush 43 might occur in adverse circumstances.This movement is commonly known as "back lash".

It is possible to reduce back lash by forming two slots in the tappedbush 43 as shown in FIGS. 3c and 3e. This ensures contact between bothsides of the threaded portion 35 and tapped bush 43. Under an axialforce from the conical nut 40 and/or from the lock nut 39a, the centreportion between the two slots will bend, marginally shortening theoverall length split bush 43, until contact is made with both sides ofthe threaded portion 35 of shank 4.

Alternatively, the split bush 43 may be formed in first and second bushparts 43a, 43b as shown in FIG. 3d. Again, this ensures contact betweenboth sides of first threaded portion 35 and the tapped bush 43. In use,the first threaded portion 35 will enter the second bush part 43b butwill not protrude through the end. This enables the lock nut 39a to urgethe second bush part 43b towards the first bush part 43a and providecontact on both sides of the threaded portion 35 of the shank 4.

Referring again to FIGS. 3a and 3b, the threaded portion 36 is shaped tomate with a similar thread form formed within the conical nut 40. Theouter surface 41 of the nut 40 is marked with calibration markings.

The second threaded portion 36 is a right hand thread form, and thefirst threaded portion 35 is a multi-start left hand thread form. Thethread directions of threaded portions 35, 36 are for right handedplayers. The directions of threads would be reversed for left handedplayers.

The end portion 42 of the shank portion 4 connected to the shaft 3,either by being formed integrally with the shaft (for example by bendingthe end of the shaft to create the shank portion) or by a joiningtechnique (for example a mechanical joining technique or by welding,brazing or by means of a bonding agent). The end portion 42 has areduced diameter to allow adhesive fixing of the shank 4 into the boreof a tube 70 (see FIG. 4) which forms the shaft. Both shank 4 and tube70 are formed with elbows 6, 7 which are in opposite senses to oneanother.

In order to adjust the angle of the golf club head relative to theshaft, conical nut 40 may be rotated the desired amount measured by thecalibration markings 41.

From FIG. 1 is can be seen that if the axis 100 of shaft 3 is extendeddownwards it intersects with through a point 25 positioned towards thesecond heel end of the club head 2, the second shank axis or bore axis.Assume that the angle between the horizontal ground and the shaft 3 is60° and the bore axis is vertical, then rotating the shaft 3 around thebore axis will result in loft angle as follows.

1. Assume shaft 3 is rotated 90° from the mean position in ananticlockwise direction as shown FIG. 2a, then from an initial position2b where the loft is about 30° the loft will change to 30°-[90°-60°],that is to 0° loft.

2. If the shaft is then rotated from the mean position in a clockwisedirection the loft will increase to 30°+[90°-60°], that is to 60° loft.

Intermediate angles of loft can be achieved by rotating the shaft 3about the bore axis to an appropriate position.

Typical relative position are as follows:

    ______________________________________                                        Club            Loft       Shaft Position                                     ______________________________________                                        Driving iron    17° 22°                                         3               20° 17°                                         4               23° 12°                                         5               26° 7°                                          6               29° 2°                                          [mean]          30° 0°                                          7               32° 3°                                          8               35° 8°                                          9               39° 15°                                         Pitching wedge  43° 22°                                         General wedge   50° 40°                                         ______________________________________                                    

Typical shaft rotation is 5° between each club selection. In order toprovide an easy to read calibration a twin screw assembly is used asfollows.

Thread 35 and thread 36 are both located on the shaft which through thebore.

Thread 35 is a left handed multi start thread e.g. 4 start, 5 mm leadwhilst thread 36 is a right handed single start thread, for example 1 mmpitch.

This combination of left and right handed threads provide a lockingaction when a force is applied to the face of the club head for righthanded players. Appropriate reversal of features will be required forleft handed players.

Because of the difference in pitch length between the shaft rotating inthe bore bush and the nut 40 small angular rotation of the shaft 3 aboutthe bore axis can be obtained from significantly larger angular rotationof the calibrated locking nut 40.

For example, typical angular rotation of the shaft 3 about the borecentre-line from say a No 6 Iron to a No 7 Iron is 5°. However, theangle of the rotation of the nut 40 relative to the shaft is magnifiedby the ratio of 5 mm lead to 1 mm pitch ie 5:1 therefore the angle ofrotation of the nut 40 to achieve a loft change from a No 6 Iron to a No7 Iron is 5×50=25°.

In order to provide a full range of club selection positions the nut 40carries a suitable range of calibrated marks 41 which when alignedagainst a fixed mark 42 on the shaft knuckle 4 provides the requiredloft angle when the bush 43, and hence the club head, is rotated to meetthe nut 40.

Referring to FIGS. 4a to 4d, further parts of the golf club are shown inmore detail. The shaft comprises upper and lower tube sections. The endportion 9 of tube 70 is attached to the smaller end of the shaft 3 atthe bottom of the lower tube section 51 by means of a hollow tube 53,which is shaped to fit internally within the tube section. The largerdiameter end 54 of the lower tube section 51 is split and flared toprovide location for the lower tube section 51 as it slides inside uppertube section (which also has a stepped bore). The upper section of theshaft 3 has a hand grip 56 on one end. At the other end of upper section3 a second adjustment means in the form of a shaft locking device 57 ismounted. The shaft locking device comprises a body 58 providedinternally with two anti-expansion rings 59 spaced on either side of anelastic tube 60. In operation the lower tube section passes through thebore of the rings 59 and the nut 61 freely when the elastic tube 60 isin free state. The nut 61 is provided with a screwed portion to engagewith a mating internal thread in the body 58 and provide clamping meansto the elastic tube 60. When clamped longitudinally, the elastic tube 60provides radial pressure to the external surface of the tube section 51and the internal surface of body 58 and so locks the two againstmovement.

Referring to FIG. 4d, an alternative locking device 57a is shown whereinternal rings 59 and a flexible tube 60 are equivalent to those inlocking device 57 shown in FIG. 4c. A nut 61a is provided with aninternal thread to mate with an external threaded portion on the body58a.

FIG. 4a shows a separate flared tube 54a which can be used optionally inplace of the flared end 54 of the tube section 51. The flared tube isproduced from appropriately size tube longitudinally split in severalpositions around the diameter and along the centre portion length of thetube. The centre tube is then increased in diameter to form a "barrel"spring which locates shaft 51 as it slides inside shaft 55.

In order to adjust the length of the shaft, a shaft locking device 57may be relaxed by unscrewing nut 61 to release the clamping force onflexible tube 60. With the locking device relaxed, shaft portion 51 canbe slid within shaft portion 55 until the required shaft length has beenobtained. This is indicated by calibration marks marked on the outersurface of shaft portion 51. Once the required length has been obtainedlocking device 57 is operated by tightening nut 61.

Referring to FIGS. 5a, 5b and 5c, a further alternative locking devicefor a telescoping shaft is shown. The locking device comprises a splitcollet. The collet 70 is split at both ends and is highly resilient as aresult. The split collet 70 is arranged to fit inside a conical sleeve72 is attached to the upper shaft and which has a tapered bore with itssmaller diameter end pointing towards the upper shaft. The split colletis held in place in an outer sleeve 73 by a circlip 74. Movement of theouter and conical sleeves towards one another causes inward deformationof the collet into contact with the surface of the lower shaft, to holdthe upper and lower shafts axially relative to one another.

FIG. 6 shows an alternative locking arrangement for the joint betweenthe head 2 and the shank 4 which can be incorporated in the club shownin FIG. 1 in place of the components shown in FIG. 3. As in the FIG. 3construction, the shank extends through a bore in the head and isfastened therein by means of a fastener 69 at its lower end. The lockingarrangement comprises castellated collar portions 72 on the head 2 andthe shank portion 4, and an intermediate collar 88 which bearscastellations 70 corresponding to the castellations 72 on the head andthe shank with which they interfit. The spacings between thecastellations on the head and the shank portion respectively (and thecorresponding facing surfaces of the intermediate collar) are different,allowing a greater range of degrees of rotation of the head around theshank.

Adjustment of the collar arrangement is achieved by loosening thefastener 69 allowing the shaft to be withdrawn partially from the borein the head and the collar portions 72 on the head and the shaft and theintermediate collar 88 to be separated axially. The collar portions andthe intermediate collar can then be rotated relative to one anotherbefore being pushed together axially and fastened together axially bymeans of the fastener 69.

What is claimed is:
 1. A golf club which comprises (a) a shaft with ashaft axis, (b) a head which has a heel end and a club face forcontacting a golf ball when the club is swung in use, and (c) a shankwhich has first and second sections, in which the first shank sectiondefines a shank axis with the head being attached at its heel end to thefirst shank section so that it can be rotated around the shank axis, andin which the second shank section extends between the shaft and thefirst shank section, the configuration of the first and second shanksections being such that the shaft axis and the shank axis intersect atabout the bottom of the heel end of the club head, so that rotating theclub head around the shank axis causes the angle between the club faceand the shaft to change, the shank being configured so that the firstshank axis is substantially vertical when the club is held in itsintended position for striking a ball.
 2. A golf club as claimed inclaim 1, in which the shank of the shaft is formed by bending an endportion of the shaft.
 3. A golf club as claimed in claim 2, in which theangle between the first and second sections of the shank is less thanthe angle between the said second section and the shaft.
 4. A golf clubas claimed in claim 3, which includes means for locking the club headagainst rotation about the shank axis.
 5. A golf club as claimed inclaim 4, in which one of the head and the shank provides a spigot andthe other of the head and the shank portion defines a bore, the head andthe shank portion engaging one another by receipt of the spigot in thebore.
 6. A golf club as claimed in claim 5, in which the spigot has (a)a first threaded portion for engaging a thread in the bore, (b) a secondthreaded portion which is threaded in the opposite sense to the firstthreaded portion, and (c) an internally threaded nut on the secondthreaded portion to lock the head against rotation relative to the shankportion.
 7. A golf club as claimed in claim 6, in which the pitch of thethread on the first threaded portion of the spigot is coarser than thatof the thread on the second threaded portion.
 8. A golf club as claimedin claim 7, in which the length of the shaft is adjustable.
 9. A golfclub as claimed in claim 8, in which the shaft comprises an innerportion and an outer portion, the inner portion being slidabletelescopically within the outer portion to adjust the length of theshaft.
 10. A golf club as claimed in claim 9, which includes aresiliently deformable member arranged around the inner portion of theshaft, between the inner portion and the internal wall of the outerportion.
 11. A golf club as claimed in claim 1, in which the shank ofthe shaft is formed by bending an end portion of the shaft.
 12. A golfclub as claimed in claim 1, in which the angle between the first andsecond sections of the shank is less than the angle between the saidsecond section and the shaft.
 13. A golf club as claimed in claim 1,which includes means for locking the club head against rotation aboutthe shank axis.
 14. A golf club as claimed in claim 1, in which one ofthe head and the shank portion provides a spigot and the other of thehead and the shank portion defines a bore, the head and the shankengaging one another by receipt of the spigot in the bore.
 15. A golfclub as claimed in claim 1, in which the length of the shaft isadjustable.